Roller type hemming apparatus

ABSTRACT

A roller type hemming apparatus includes a support member having a slide bore, a compression pad of a block-like shape, and a slide member. The compression pad and the slide member are received in the slide bore such that the compression pad is intermediate the support member and the slide member. The compression pad and slide member are preloaded therein. The apparatus further includes a stop member having a radially projecting head. The stop member fastens the compression pad and the slide member to the support member. The apparatus also includes a hem roller. The slide member includes a flange projecting from an outer surface of the slide member and the hem roller is rotatably mounted on the flange. The movement of the slide member is tempered during the application of an abrupt compressive force.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the priority of U.S. Provisional Application No. 60/557,601 filed Mar. 30, 2004.

TECHNICAL FIELD

This invention relates to a roller type hemming apparatus for edge hemming vehicle closure panels, such as hemming of door panels, hood panels, and decklid panels.

BACKGROUND OF THE INVENTION

It is known in the art relating to hemming that roller hemmers can be used to hem the edges of metal, for example aluminum, automotive parts such as door panels, hood panels, and decklid panels.

Conventionally, a hemming apparatus may be mounted to a multi-axis controllable robot and may include a hem roller carried by a support. The conventional hemming apparatus is adapted for hemming a bent portion of a workpiece, such as a door panel, positioned on a hemming die, by rotating the hem roller under pressure along the bent portion. The conventional roller type hemming apparatus can thus be used for continuous hemming along the contour of the edge of the workpiece.

In order to achieve good hemming with such a conventional hemming apparatus, however, the robot must move the hem roller along the edge of the workpiece at a constant distance from the hemming die. The robot is not composed of a perfectly rigid body, and when the hem roller is positioned against the edge of the workpiece, the robot may be deflected by its own resiliency or by a repulsive force exerted by the edge of the workpiece itself. This results in an interrupted pressing force applied by the hem roller and therefore imperfect hemming of the workpiece. Springs have been disposed in the hemming roller support to compensate for the interrupted pressing force, but alone springs have proven inefficient and unpredictable.

Further, the edge of a workpiece to be hemmed may also have a complex configuration. This makes it difficult for a conventional hemming apparatus to achieve adequate hemming of the workpiece.

SUMMARY OF THE INVENTION

The present invention provides a roller type hemming apparatus which includes a hem roller that can accurately follow up the configuration of a bent portion of a workpiece to be hemmed and more accurately and uninterruptably apply a consistent hemming force.

The present invention also provides a roller type hemming apparatus wherein deflection of the hem roller is limited while the hemming force is maintained by a compression pad having a predetermined compressible constant.

More particularly, a roller type hemming apparatus includes a support member having a slide bore, a compression pad of a block-like shape, and a slide member. The compression pad and the slide member are received in the slide bore such that the compression pad is intermediate the support member and the slide member. The compression pad and slide member are preloaded therein. The apparatus further includes a stop member having a radially projecting head. The stop member fastens the compression pad and the slide member to the support member. The apparatus also includes a hem roller. The slide member includes a flange projecting from an outer surface of the slide member and the hem roller is rotatably mounted on the flange. The movement of the slide member is tempered during the application of an abrupt compressive force.

In a specific embodiment, the slide member flange may include an aperture, the hem roller may include a central opening and a bushing therein the central opening, and the apparatus may include a shaft extending through the bushing and the flange aperture. The apparatus may also include a nut for securing the shaft to the slide member flange and a collar on the shaft disposed between the hem roller and the slide member flange.

The stop member may be a bolt having a central shank portion and a threaded portion on an end opposite the radially projecting head. The slide member may include a threaded hole on an inner surface thereof for receiving the threaded portion of the stop member. The shank portion of the stop member may pass through the compression pad. The support member may include a circular opening for receiving the stop member, the circular opening being smaller in diameter than the head of the stop member and extending from an outer surface of the support member to the support member slide bore. The support member circular opening may be coaxially formed in relation to the support member slide bore.

The support member slide bore may have a square cross-sectional shape. The slide member may have a square cross-sectional shape smaller than the cross section of the support member. The apparatus may further include a spacer plate removably fastened to an outer surface of the support member between the outer surface and the stop member head. The compression pad may be a urethane block. The apparatus may be adapted for operable connection to a work arm of a multi-axis robot and may be fastened to a forward end of a hand of the robot.

With the above construction, as the hem roller is displaceable in a direction corresponding to the pressing direction of the robot hand, deflection of the robot hand or any difference between the traveling path of the robot hand and the peripheral contour of the workpiece can be absorbed, permitting the hem roller to accurately follow the bent portion of the workpiece.

These and other features and advantages of the invention will be more fully understood from the following detailed description of the invention taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is an environmental view of a roller type hemming apparatus in accordance with the present invention hemming a workpiece with the aid of a robot hand;

FIG. 2 is a sectional view of a hem roller support of the roller type hemming apparatus of FIG. 1;

FIG. 3 is a perspective view illustrating a teaching operation; and

FIG. 4 is a perspective view illustrating a hemming operation.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings in detail and to FIG. 1 in particular, a roller type hemming apparatus 10 in accordance with the present invention is adapted for operable connection to a work arm, such as a multi-axis controllable robot hand 12, to which a predetermined traveling path is preliminarily taught. The roller type hemming apparatus 10 includes a hem roller support 14 mounted on a forward end of the robot hand 12, and a hem roller 16 displaceably supported by the hem roller support 14 to be pressed against a workpiece W.

The workpiece W is, for example, a door panel composed of an outer panel Wo and an inner panel Wi. The outer panel Wo has a peripheral portion preliminarily bent upwardly substantially at right angles, and the inner panel Wi has a peripheral stepped portion extending outwardly. The outer panel Wo and the inner panel Wi are placed on a lower die 18 with the stepped portion of the inner panel Wi arranged along the inside of the bent portion of the outer panel Wo. The lower die 18 has an upper surface constituting a forming surface 20 and is placed on a common base 22 on which the hemming apparatus 10 is placed at a predetermined distance away from the lower die 18. The workpiece W is placed on the forming surface 20 of the lower die 18 and is secured thereto by fixtures 24.

As the robot hand 12 is well known in the art, its description will be omitted, and the hem roller support 14 and the hem roller 16 will be described in detail.

As shown in FIG. 2, a support member 26 is attached to the forward end of the robot hand 12 by fasteners such as bolts 28. The support member 26 has a slide bore 30. The slide bore 30 may have a square cross-sectional shape. A compression pad 32 of a block-like shape, such as a urethane block or similar, is inserted into the support member 26 slide bore 30. Then slide member 34 is slidably inserted in the support member 26. The slide member 34 may be a substantially prismatic member slidably inserted in the slide bore 30 of the support member 26. The slide member 34 may also have a square cross-sectional shape smaller than the cross-section of the support member 26. A stop member 36 having a radially projecting head 38 fastens the compression pad 32 and the slide member 34 to the support member 26.

The slide member 34 includes a flange 40 projecting downwardly (as viewed in FIG. 2) from an outer surface 42 of the slide member. The hem roller 16 is rotatably mounted on the flange 40. The slide member flange 40 may include an aperture 44 of a predetermined diameter extending through a thickness direction thereof. The hem roller 16 may include a central opening 46 and a bushing 48 therein. The bushing 48 may be made from a metallic, plastic, ceramic or similar material. The hem roller 16 may then be mounted on the flange by a shaft 50 extending through the bushing 48 and the flange aperture 44. A nut 52 secures the shaft 50 to the flange 40. A collar 54 may be disposed between the hem roller 16 and the slide member flange 40.

The compression pad 32 may have a predetermined compression constant. The compression pad 32 has upper and lower ends held in abutment against a lower surface of the support member 26 and an upper surface of the slide member 34, respectively, so as to urge the slide member 34 downwardly (as viewed in FIG. 2) in the support member 26. The movement of the preloaded slide member 34 is thereby tempered by the compression pad 32 during the application of an abrupt compressive force, such as a force applied to the hem roller 16.

The stop member 36 may be a bolt having a central shank portion 56 and a threaded portion 58 on an end opposite the radially projecting head 38. The slide member 34 may include a threaded hole 60 on an inner surface thereof for receiving the threaded portion 58 of the stop member 36. The shank portion 56 of the stop member may pass through the compression pad 32. The support member 26 may include a circular opening 62 for receiving the stop member 36. The circular opening 62 is smaller in diameter than the head 38 of the stop member 36 and extends from an outer surface of the support member 26 to the support member slide bore 30. The circular opening 62 may also be coaxially formed in relation to the support member slide bore 30. A spacer plate 64 of a predetermined thickness t may be removably fastened by a set screw 66 to an outer surface of the support member between the outer surface and the stop member head 38. The spacer plate 64 may include an opening 68 for receiving the stop member 36, the opening being smaller in diameter than the stop member head 38.

A teaching procedure for the robot hand 12 will now be described with reference to FIG. 3. The spacer plate 64 is preliminarily interposed between the support member 26 and the head 38 of the stop member 36, as shown in FIG. 3. This causes the slide member 34 and consequently the hem roller 16 to be displaced upwardly with respect to the support member 26 or in a direction away from the forming surface 20 of the lower die 18, by a distance corresponding to the thickness t of the spacer plate 64.

Then, the hem roller 16 is moved along the forming surface 20 of the lower die 18 in abutment therewith so as to teach the robot hand 12 a virtual traveling path defined by the forming surface 20. The position of the hem roller 16 with respect to the forming surface 20 at this time is shown as teaching level LT. After the teaching operation has been completed, the spacer plate 64 is removed to return the slide member 34 to a free position where the head 38 of the stop member 36 is in abutment against the upper surface of the support member 26.

As described above, in teaching the robot hand 12, the virtual traveling path temporarily defined by the forming surface 20 of the lower die 18 is taught to the robot hand 12, so that the robot hand 12 is shifted in the traveling path thus taught to perform a hemming operation.

During the hemming operation, the workpiece W is placed on the forming surface 20 of the lower die 18, as shown in FIG. 4, so that the hemming level LH which defines an ideal traveling path of the hem roller 16 is deviated by a distance α from the teaching level LT in a direction away from the forming surface 20 of the lower die 18. The distance α corresponds to thickness δ of the workpiece W which is the total of twice the thickness of the outer panel Wo and the thickness of the inner panel Wi. Here, it is to be noted that the robot hand 12 is so moved as to locate the hem roller 16 at the teaching level LT. However, the hem roller 16 cannot be located at the level LT since the spacer plate 64 is removed during the hemming operation, and since the workpiece W is placed between the hem roller 16 and the lower die 18. Then, the compression pad 32 provided between the support member 26 and the slide member 34 is contracted to the amount of difference in height of the hem roller 16, that is, the total of the thickness t of the spacer plate 64 and the thickness 6 of the workpiece W. As the compression pad 32 is contracted, the hem roller 16 is pressed toward the lower die 18 by a repulsive force of the contracting compression pad 32. Specifically, the difference between the teaching level LT and the hemming level LH is absorbed by contraction of the compression pad 32, so that a good hemming operation may be performed even though the virtual traveling path temporarily defined by the forming surface 20 of the lower die 18 has been taught to the robot hand 12.

Further, during the hemming operation, the hem roller 16 is pressed with a predetermined pressing force against the bent portion of the workpiece W, and a repulsive force of the bent portion causes the robot hand 12 to be deflected in a direction away from the bent portion. As, in teaching to the robot hand 12, the position of the slide member 34 has been displaced with respect to the support member 26 by a distance corresponding to the thickness t of the spacer plate 64, the hem roller 16 can be maintained on the hemming level LH, even when the robot hand 12 is deflected within the range limited by the maximum distance corresponding to the thickness t. Thus, the deflection of the robot hand 12 is absorbed and the hem roller 16 is always held on the hemming level LH, permitting the pressing force of the hem roller 16 to be maintained at a proper value to achieve good hemming.

As described above, as the slide member 34 and consequently the hem roller 16 is displaceable with respect to the support member 26 and consequently the robot hand 12, deflection of the robot hand 12, or the difference in the traveling path of the hem roller 16 with respect to the workpiece W can be absorbed. This permits the hem roller 16 to constantly follow up the bent portion of the workpiece W exactly and to be constantly pressed with a proper pressing force for good hemming.

Further, as the hem roller 16 is displaceable with respect to the robot hand 12, the teaching procedure can be readily performed, using the forming surface 20 of the lower die 18 as a virtual traveling path.

It is essential to the present invention that the hem roller 16 be displaceable with respect to the robot hand 12, the position of the hem roller 16 being controlled by the position controlling means of the hem roller support 14. Therefore, teaching of the robot hand 12 can be readily carried out, and during the hemming operation, the position of hem roller 16 can be constantly held on the hemming level LH to achieve good hemming at all times.

Thus, in the hemming apparatus of the present invention, as the hem roller is rotated under a proper pressing force in an accurate traveling path along the peripheral contour of a workpiece, hemming can always be satisfactorily carried out. In addition, teaching of the robot hand can be readily carried out in the present invention.

Although the invention has been described by reference to a specific embodiment, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiment, but that it have the full scope defined by the language of the following claims. 

1. A roller type hemming apparatus comprising: a support member having a slide bore; a compression pad of a block-like shape; a slide member; said compression pad and said slide member being received in said slide bore such that said compression pad is intermediate said support member and said slide member and being preloaded therein; a stop member having a radially projecting head, said stop member fastening said compression pad and said slide member to said support member; and a hem roller; said slide member including a flange projecting from an outer surface of said slide member, said hem roller being rotatably mounted on said flange; whereby the movement of the slide member is tempered during the application of an abrupt compressive force.
 2. The roller type hemming apparatus of claim 1, wherein said slide member flange includes an aperture, said hem roller includes a central opening and a bushing therein said central opening, and said apparatus includes a shaft extending through said bushing and said flange aperture.
 3. The roller type hemming apparatus of claim 2, further including a nut for securing said shaft to said slide member flange.
 4. The roller type hemming apparatus of claim 2, further including a collar on said shaft disposed between said hem roller and said slide member flange.
 5. The roller type hemming apparatus of claim 1, wherein said stop member is a bolt having a central shank portion and a threaded portion on an end opposite said radially projecting head.
 6. The roller type hemming apparatus of claim 5, wherein said slide member includes a threaded hole on an inner surface thereof for receiving the threaded portion of said stop member.
 7. The roller type hemming apparatus of claim 5, wherein said shank portion of said stop member passes through said compression pad.
 8. The roller type hemming apparatus of claim 1, wherein said support member includes a circular opening for receiving said stop member, said circular opening being smaller in diameter than the head of said stop member and extending from an outer surface of said support member to said support member slide bore.
 9. The roller type hemming apparatus of claim 8, wherein said support member circular opening is coaxially formed in relation to said support member slide bore.
 10. The roller type hemming apparatus of claim 1, wherein said support member slide bore has a square cross-sectional shape.
 11. The roller type hemming apparatus of claim 10, wherein slide member has a square cross-sectional shape smaller than said cross section of said support member.
 12. The roller type hemming apparatus of claim 1, further including a spacer plate removably fastened to an outer surface of said support member between said outer surface and said stop member head.
 13. The roller type hemming apparatus of claim 12, wherein said spacer plate includes an opening for receiving said stop member, said opening being smaller in diameter than said stop member head.
 14. The roller type hemming apparatus of claim 1, wherein said compression pad is a urethane block.
 15. The roller type hemming apparatus of claim 1, wherein said apparatus is adapted for operable connection to a work arm of a multi-axis robot.
 16. The roller type hemming apparatus of claim 15, wherein said apparatus is fastened to a forward end of a hand of said robot.
 17. A method of roller hemming, the method comprising the step of: providing a roller type hemming apparatus including: a support member having a slide bore; a compression pad of a block-like shape; a slide member; said compression pad and said slide member being received in said slide bore such that said compression pad is intermediate said support member and said slide member and being preloaded therein; a stop member having a radially projecting head, said stop member fastening said compression pad and said slide member to said support member; and a hem roller; said slide member including a flange projecting from an outer surface of said slide member, said hem roller being rotatably mounted on said flange; whereby the movement of the slide member is tempered during the application of an abrupt compressive force. 